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Utility classes and methods developed for Brooklyn but not dependendent on Brooklyn or much else
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.brooklyn.util.guava;

import java.util.Map;

import javax.annotation.Nullable;

import com.google.common.collect.ImmutableMap;
import com.google.common.reflect.TypeToken;

public class TypeTokens {

    // creating TypeToken is surprisingly expensive so cache these common ones
    public static final Map, TypeToken> COMMON_TYPE_TOKENS = ImmutableMap., TypeToken>builder()
        .put(String.class, TypeToken.of(String.class))
        .put(Object.class, TypeToken.of(Object.class))
        .put(Integer.class, TypeToken.of(Integer.class))
        .put(Boolean.class, TypeToken.of(Boolean.class))
        .put(Double.class, TypeToken.of(Double.class))
        .put(Long.class, TypeToken.of(Long.class))
        .build();
    
    /** returns raw type, if it's raw, else null;
     * used e.g. to set only one of the raw type or the type token,
     * for instance to make serialized output nicer */
    @Nullable
    public static  Class getRawTypeIfRaw(@Nullable TypeToken type) {
        if (type==null || !type.equals(TypeToken.of(type.getRawType()))) {
            return null;
        } else {
            return type.getRawType();
        }
    }
    
    /** returns null if it's raw, else the type token */
    @Nullable
    public static  TypeToken getTypeTokenIfNotRaw(@Nullable TypeToken type) {
        if (type==null || type.equals(TypeToken.of(type.getRawType()))) {
            return null;
        } else {
            return type;
        }
    }
    
    /** given either a token or a raw type, returns the raw type */
    @SuppressWarnings("unchecked")
    public static  Class getRawType(TypeToken token, Class raw) {
        if (raw!=null) return raw;
        if (token!=null) return (Class) token.getRawType();
        throw new IllegalStateException("Both indicators of type are null");
    }
    
    
    /** given either a token or a raw type, returns the token */
    @SuppressWarnings("unchecked")
    public static  TypeToken getTypeToken(TypeToken token, Class raw) {
        if (token!=null) return token;
        if (raw!=null) {
            TypeToken result = COMMON_TYPE_TOKENS.get(raw);
            if (result==null) result = TypeToken.of((Class)raw);
            return (TypeToken) result;
        }
        throw new IllegalStateException("Both indicators of type are null");
    }

    /** gets the Class object from a token; normal methods return Class which may technically be correct 
     * with generics but this sloppily but handily gives you Class which is usually what you have anyway */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static  Class getRawRawType(TypeToken token) {
        return (Class)token.getRawType();
    }

    /** Checks that if both type and token are supplied, either exactly one is null, or 
     * they both refer to the same non-null type */
    public static  void checkCompatibleOneNonNull(Class type, TypeToken typeToken) {
        if ((type==null && typeToken!=null) || (type!=null && typeToken==null)) {
            return;
        }
        if (type==null && typeToken==null) {
            throw new NullPointerException("Type not set (neither class or type token)");
        }
        if (!type.equals(typeToken.getRawType())) {
            throw new IllegalStateException("Invalid types, token is "+typeToken+" (raw "+typeToken.getRawType()+") but class is "+type);
        }
    }
    
}